The prior art includes the use of hinges of the sort specified above, especially in the sector of kitchen and office furniture, where the hinges are required to give good support to the doors and at the same time to ensure effective snap-action closing of the doors even after a large number of repeated actuations.
These hinges must also be simple and inexpensive to produce since, for reasons of competition, the sale price of the hinges cannot be high and they are produced industrially in large quantities.
In conventional hinges the hinged end of the hinge arm comprises an endmost eye which is made by bending part of the hinge arm itself, the eye being intended to house the hinge pin. Mounted coaxially around this end is a cam, which is generally made of a plastic material, on which the spring means are to act in order to allow snap-action closing of the hinge.
It must be pointed out, however, that the con-struction of the moulds necessary to produce a cam shaped internally so as to fit around the end of the hinge arm and externally so as to present bearing surfaces for the spring means, is not only complicated but is also no small task in itself and involves an increase in the cost of producing each hinge.
Hinges are also known in which the hinged end of the hinge arm is bent in such a way as to form, alongside a central endmost eye, two lateral portions which themselves form a cam for the spring means of the hinge.
These hinges, though simple to make, have the drawback that during opening and closing of the hinge the spring means are acting directly on, by sliding over, the abovementioned lateral portions of the hinge arm. Accordingly, in order to prevent the performance of the hinge from being compromised after a limited number of actuations, the hinge arm is made from high-carbon temperable steels, so that the hinge arm can be subjected to thermal treatment of tempering after being formed. Clearly, however, the use of temperable steels and the need to subject the hinge arm to a final tempering treatment raises the manufacturing costs of the hinges.
The alternative solution of making the hinge arm from materials having better mechanical properties, so as to ensure good wear resistance of the lateral portions of the hinge arm without having to perform heat treatments, is not practicable owing to the fact that the hinge arm is cold-worked by mechanical deformation.
It is an object of the present invention to provide a snap-action hinge for the opening and closing of furniture doors and the like, that is simple and inexpensive to produce and has structural and functional characteristics such as to overcome the drawbacks cited above with reference to the prior art.